Amino-functional siloxanes are widely used as constituents of textile-reconditioning compositions, more particularly of textile-softening compositions, as constituents of laundry detergent or cleaning compositions for textiles and hydrophobicizing agents. A multiplicity of structural variations of this group of compounds are described in the prior art and are obtainable via different routes. However, terminally amino-modified, purely linear polydimethylsiloxanes cannot be varied in their degree of modification in the course of preparation. This is disadvantageous because not only the number of the amino groups but also their type has considerable influence on the aminopolysiloxane's substantivity, i.e. the ability to bind to carriers such as keratinic substances for example, or else to textiles. The total nitrogen content of an aminosiloxane is an important parameter because it correlates directly with the substantivity of the aminosiloxane.
ABn multiblock copolymers are described for extending the polymer chain without reducing the number of amino functionalities. However, as chain length increases, linear copolymers become very viscous and hence difficult to handle. U.S. Pat. No. 5,807,956 and U.S. Pat. No. 5,981,681 teach non-hydrolyzable block copolymers of the (AB)nA type with alternating units consisting of polysiloxane and amino-polyalkyleneoxide. They are prepared by linking α,Ω-dihydrogenpolydimethylsiloxanes to epoxy-bearing olefins in SiC fashion by nobel metal-catalyzed hydrosilation and reacting the resulting epoxy-terminated siloxanes with amino-terminated polyalkylene oxides. Alternatively, α,Ω-dihydrogenpolydimethyl-siloxanes are linked to epoxy-terminated allyl polyethers by hydrosilation and the epoxy-functionalized siloxanes thus obtained are subsequently reacted with diamines.
Polysiloxanes having high degrees of modification combined with a chain length which can be varied irrespective of the nitrogen content are obtainable by lateral functionalization of a polysiloxane with amino-containing organic substituents.
The prior art discloses a multiplicity of references dealing with laterally modified aminosiloxanes. Laterally modified aminosiloxanes are obtainable under base catalysis or under acid catalysis. Preparation by base-catalyzed equilibration, as described in paragraphs [0154] and [0155] in EP 1 972 330 (U.S. Patent Appl. Pub. 2011-104085) for example, can lead, depending on the starting materials used, either to terminally dihydroxy-functional, laterally amino-modified polysiloxanes, or to laterally amino-modified polysiloxanes endblocked with trimethylsilyl groups. Such endblocked polysiloxanes, when compared with their structural analogues having free SiOH groups, not only have superior storage stability in the absence of a solvent, but also prevent gellike precipitations and accretions in the handling of aqueous emulsions of such polysiloxanes. These gel deposits are particularly unwelcome for applications in the textile sector.
An acid-catalyzed condensation polymerization according to the prior art, as represented in U.S. Pat. No. 7,238,768 B2 for example, leads to amino-modified polysiloxanes having hydroxyl groups or alkoxy groups at their chain ends. True, the process has lower reaction temperatures and shorter reaction times and hence is advantageous compared with base-catalyzed equilibrations, but this more economical manufacturing process is responsible for the reduced hydrolytic stability of these non-endblocked siloxanes due to the absent trimethylsilyl end groups.
Amino-functional polysiloxanes are undergoing constant improvement in order that the textile fabrics treated therewith may be endowed with advantageous effects, for example a textile-softening effect and crease resistance, and/or to reduce the harmful or negative effects which can arise in the course of cleaning and/or conditioning and/or wearing, for example fading, greying, etc. In addition, sufficient hydrophilicity shall be achieved for the fabric as well as good softness. It is a further disadvantage of textile-softening formulations based on polysiloxanes of the prior art that the softening property of a fabric finished therewith may in the worst case be lost after just a single wash. There is accordingly a need for textile-softening polysiloxanes having enhanced durability on textiles both in the OEM finishing of textile manufacture and in cleaning and reconditioning, for example in the rinse cycle softening of a washing machine.
This increases the need for the production process to provide structurally precisely defined polymers whose nitrogen content, type and quantity of amino groups and whose chain length can be independently varied via the recipe. At the same time, however, the production process shall safeguard the consistent composition and reproducible quality for the amino-containing polymers with regard to the particular application.
U.S. Pat. No. 6,171,515 B1 describes endblocked and also dialkoxy-functional aminopolysiloxanes which, in a synthesis step subsequent to the siloxane polymerization, undergo a functionalization of the primary and secondary amino groups with epoxy-functional monomers such as glycidol for example. A similar functionalization of aminosiloxanes with alkylene oxides is described in EP0399706. Further functionalizations of amino-functional polysiloxanes with glycerol carbonate or gluconolactone are described in EP 1 972 330 and in J. Phys. Chem. B 2010, 114, 6872-6877.
For enhanced substantivity, JP 2002-167437-A describes laterally guanidino-functionalized polysiloxanes prepared by reacting the corresponding aminopolysiloxanes with cyanamide. WO 2006/081927 describes the condensation copolymerization of a dihydroxy-functional polydimethylsiloxane with a guanidino-containing silane and an amino-containing silane. Although a functionalization of the polysiloxane with nitrogen-containing groups that differ in type and quantity is possible in this way, WO 2006/081927 (U.S. Pat. No. 7,825,207) does not disclose any route to endblocked multiamino-functional polysiloxanes.